Purpose: A large postvoid residual (PVR) has been considered to be an indicator for the need to further management. However, the threshold level of PVR has been not defined. We determined the PVR volume by using bladder voiding efficiency (BVE) that would predict surgical outcomes after GreenLight HPS™ laser photoselective vaporization of the prostate (HPS-PVP). Methods: A total of 193 patients who underwent HPS-PVP were divided into two groups based on BVE: >75% (group A) and ≤75% (group B). BVE was calculated by dividing voided volume by voided volume plus PVR. Surgical outcomes were assessed from the ratio of the IPSS, the difference in Qmax, and the difference in the quality of life IPSS subscore (QoL) before surgery and at 3, 12, and 36 months postoperatively. Results: There were significant improvements in all outcome measures after 3, 12, and 36 months; the improvement in Qmax was greater in group A than group B at each time point. The IPSS ratio was significantly greater in group A than group B at 3 months. There was no difference in QoL between the groups. The multivariate logistic regression analysis showed that BVE correlated significantly with short-term surgical success, but not with prostate volume or age. In the area under curve of ROC analysis, the BVE cutoff value of 75% showed the highest sensitivity and specificity for predicting the short-term success of surgical outcomes. Conclusions: Our results suggest that a large PVR may predict relatively slight improvements in short-term surgical outcomes after HPS-PVP. The cutoff value of PVR in predicting surgical success is 25% or more of residual fraction.